title: Bolus administration of obestatin does not change glucose and insulin levels neither in the systemic nor in the portal circulation of the rat.
abstract: Obestatin is a second peptide derived from the preproghrelin polypeptide. It was originally thought to have anorexigenic effects, thereby functioning as an antagonist of ghrelin. However, this has been a subject of debate ever since. Since acylated ghrelin strongly induces insulin resistance, it could be hypothesized that obestatin plays a role in glucose homeostasis as well. In the present study we evaluated the effect of obestatin on glucose and insulin metabolism in the systemic and portal circulation. Obestatin 200 nmol/kg was administered systemically as a single intravenous bolus injection to fasted pentobarbital anesthetized adult male Wistar rats. Up to 50 min after administration, blood samples were taken to measure glucose and insulin concentrations, both in the portal and in the systemic circulation. The effect of obestatin was evaluated in fasted and in glucose-stimulated conditions (IVGTT) and compared to control groups treated with saline or IVGTT, respectively. Intravenous administration of obestatin did not have any effect on glucose and insulin concentrations, neither systemic nor portal, when compared to the control groups. Only the glucose peak 1 min after administration of IVGTT was slightly higher in the obestatin treated rats: 605.8+/-106.3% vs. 522.2+/-47.1% in the portal circulation, respectively (NS), and 800.7+/-78.7% vs. 549.6+/-37.0% in the systemic circulation, respectively (P<0.02), but it can be debated whether this has any clinical relevance. In the present study, we demonstrated that intravenously administered obestatin does not influence glucose and insulin concentrations, neither in the portal nor in the systemic circulation.
authors.affiliation: Department of Internal Medicine, Section of Endocrinology, Erasmus University Medical Centre, PO Box 2040, 3000 CA Rotterdam, The Netherlands. r.kiewiet@erasmusmc.nl
authors.forename: Rosalie M
authors.initials: RM
authors.lastname: Kiewiet
authors.forename: Carlotta
authors.initials: C
authors.lastname: Gauna
authors.forename: Maarten O
authors.initials: MO
authors.lastname: van Aken
authors.forename: Bedette
authors.initials: B
authors.lastname: van de Zande
authors.forename: Aart Jan
authors.initials: AJ
authors.lastname: van der Lely
mesh_terms: D000005:Abdomen / Q000098:blood supply / Q000601:surgery; D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D005215:Fasting; D005951:Glucose Tolerance Test / Q000379:methods; D007275:Injections, Intravenous / Q000379:methods; D007328:Insulin / Q000097:blood*; D007601:Jugular Veins / Q000601:surgery; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D036361:Peptide Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D011169:Portal Vein / Q000601:surgery; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010446:Peptide Fragments; D036361:Peptide Hormones; C505798:obestatin, rat